Method of preparing aminoazoledisulfides



case or cone or LAST, Pact.

United States Patent 3,100,773 METHOD OF PREPARING AMINOAZOLEDI-SULFIDES George D. Louth, Doylestown, and Marlyn J. Brock,

Akron, Ohio, assignors to The Firestone Tire & Rubber Company, Akron,Ohio, a corporation of Ohio No Drawing. Filed May 20, 1959, Ser. No.814.389 8 Claims. (Cl. 260-2411) This invention relates to thepreparation of aminoazole disulfides, also known asazolethiosulfenamides.

Aminoazole disulfides are powerful accelerators and curing agents forthe vulcanization of natural rubber and the synthetic,sulfur-vulcanizable diene rubbers. These disulfides are especiallyuseful in pneumatic tire tread stocks, in which a powerful butdelayed-action, nonscorching, curing combination is needed forsuccessful factory processing of the stocks.

The compounds produced in accordance with the present invention areaminoazole disulfides, represented by the formula in which R and R thethe same or different aliphatic, cycloaliphatic, or aralkyl groups or Rand R together form a single chain (which can contain O--, Nl-lor S-)constituting with the attached nitrogen atom a heterocyclic radical, Rcan be hydrogen, and R represents a member of the class consisting ofthiazoles, oxazoles and imidazoles.

The invention provides a method of making such aminoazole disulfides byinteracting an amine monosulfide or an amine disulfide with a Z-mercaptoazole.

The preparation reaction utilizing an amine monosulfide appears toconform to the following equation, in which Z-mercaptobenzothiazole andmorpholine monosulfide represent typical reactants:

The use of an additional mole of the mercapto azole will convert thefree amine produced by the metathesis into into the amine salt of themercapto azole, and this salt is also a vulcanization accelerator.

The preparation reaction utilizing an amine disulfide appears to conformto the following equation, in which 2- rnercaptobenzothiazole andmorpholine disulfide represent typical reactants:

Again the free amine can be converted into the amine salt by usinganother mole of the mercapto azole.

3,100,773 Patented Aug. 13, 1963 "ice It has been found that an alkalimetal salt of the mercapto azole can be substituted for the mercaptoazole in the latter of the two reactions shown above. Presumably, sodiumsulfide is formed instead of free sulfur.

The invention is illustrated by the following examples.

EXAMPLE 1 Preparation of 2-(4-Morph0linyldithio)benzothiazole Analysis:

Calculated for N-morpholinyl Found benzothiazole- 2-thiosulienamidePercent carbon 46 .50 46 .47 Percent hydrogen 4 .26 4 .29 Percentnitrogen n 9 .86 i) .97 Percent sulfur 33 .8 33 .5

The X-ray diffraction diagram of the purified product was completelydifferent from the X-ray diagrams of the starting materials and of2,2'-dithio-bis-benzothiazole.

EXAMPLE 2 Preparation of 2-(4-Morpholinyldilhio)Benzothiazole Onehundredth of a mole of morpholine disulfide (2.36 grams) was dissolvedin hot alcohol and 1.9 grams of the sodium salt ofZ-mercaptobenzothiazole (0.01 mole) was added. The first precipitatewhich formed was identified as morpholine disulfide. Upon concentrationof the alcoholic solution a second precipitate was isolated and found byX-ray analysis to contain N-morpholinyl benzothiazole-Z-thiosulfenamide(subject compound).

EXAMPLE 3 Preparation of 2- 4 -M orpholinylditkio Benzothiazole Onehundredth of a mole of morpholine disulfide (2.36 grams) and 1.67 gramsof 2-mercaptobenzothiazole (0.01 mole) were melted together. Uponcooling a viscous yellow liquid was obtained, and a morpholine odor wasdetected, indicating that a reaction had taken place. Upon stirring theliquid solidified into a pasty product. An X-ray diffraction diagram ofthis product showed the presence of the desired disulfide (subjectcompound) because of its similarity to the X ray diagram of the purifiedproduct of Example 1.

EXAMPLE 4 Preparation of 2-(4-Morpholinyldithio)Benzolhiazole Onehundredth molar quantities of morpholine mono sulfide (2.0 grams) and of2-mercaptobenzothiazole (1.67 grams) were dissolved in boilingchloroform. The solution turned dark, and morpholine issued therefrom asthe mixture boiled. Upon evaporation of the mixture to dryness a solidproduct was obtained. After purifying the product by washing with etherand drying, it melted at 131-133 C. its X-ray difiraction diagram wasidentical to that of the product of Example 1.

3 EXAMPLE 5 Preparation of 2-(4-Morpholinyldithio)Benzothiazole Molarquantities of morpholine disnlfide (236 grams) and of2-mercaptobenzothiazole (167 grams) were used for a large-scalepreparation of subject compound. The morpholine disulfide was dissolvedin hot absolute alcohol and the mercaptobenzothiazole was added. As thesolution cooled, a precipitate settled out. The precipitate wasseparated by filtration and was washed with ether. The dried productmelted at 131-133 C. It was compounded in a natural rubber tire treadstock reinforced by HAF carbon black and found to be a powerfuldelayed-action accelerator of vulcanization by free sulfur and also tobe a powerful curing agent in the absence of free sulfur and otheraccelerator.

EXAMPLE 6 Preparation of N-Morpholinyl Benzimz'dazole-Z- ThiosulfenamideOne hundredth molar quantities of morpholine disulfide 2.36 grams) andZ-mercaptobenzimidazole (1.5 grams) were dissolved in absolute alcohol.The solution turned yellow, indicating that a reaction had taken place.Part of the alcohol was boiled off, and the odor of morpholine wasdetected. A precipitate, which formed upon cooling the solution, wasseparated and dried. The X-ray diffraction diagram of this productshowed it to contain some unreacted Z-mercaptobenzimidazole and also anadditional substance different from the starting materials and believedto possess the following structure:

EXAMPLE 7 Preparation of N-Morpholinyl Benzimidazole-Z- Thz'osulfenamide Morpholine disulfide and 2-mercaptobenzimidazole weremelted together in equal molar quantities. The melt became yellow, andthe odor of morpholine was detected. The viscous liquid melt solidifiedupon stirring. The product was recrystallized from alcohol, and theX-ray diffraction diagram was obtained. The X-ray pattern showed thepresence of unreacted 2-mercaptobenzimidazole and of another substancedifferent from either of the reactants or morpholine, and thus concludedto be subject compound.

EXAMPLE 8 Preparation of N-Cyclohexyl Benzothiazole-Z- ThiosulfenamideAdditional examples of aminozole disulfides can be prepared by usingother appropriate amine monosulfides or disulfides and othermercaptoazoles in lieu of those shown in the examples. Thus,2-(dimethylaminodithio)benzothiazole is prepared by reactingZ-mercaptobenzothiamole with dimethylamine disulfide;Z-(di-n-propylaminodithio) benzothiazole is made fromN,N'dithio-bis-di-n-propylamine and Z-mercaptobenzothiazole; andZ-(n-butylaminodithio)-(4,5-dimethylthiazole) is prepared by reactingN,N-dithio-bis-n-butylamine with 2-mercapto-4,5-dimethylthiaziole.

The amine sulfides utilized in the invention can be illustrated by theformula in which the Rs are the same or different aliphatic,cycloaliphatic or aralkyl radicals, one R on each nitrogen can behydrogen, the two Rs on one or both nitrogen atoms are joined to form asingle chain (which can contain --O-, NH-- or S) constituting with theattached nitrogen atom a heterocyclic radical, and x represents one ofthe integers 1 and 2.

Other amine sulfides in addition to those disclosed hereinabove are thefollowing:

N,N'-thio-bis-dimethylamine N,N-thio-bis-diethylamine N,N-thio-bis-di-n-propylamine N,N'-thio-bis-di-n-butylamineN,N'-thio-b-is-di-isobutylamine N,N-thio-bis-di-n-amylamineN,Nthio-bis-di-isoamylamine N,N'-thio-bis-di-n-hexylamineN,N'-thio-bis-di-n-heptylamine N,N'-thiQ-biSHdi-n-octyIamineN,N'-thio-bis-di-benzylamine N,N'-thio-bis-methyl cyclohexylamineN,N'-thio-bis-ethyl cyclohexylamine N,N'-thio-bis-(thiomorpholine)N,N'-thio-bis-(4-N-ethyl piperazine) N,N'-thio-bis-piperidineN,N-thio-bis-pyrrolidine N,N-dithio-bis-diethylamineN,Ndithio-bis-di-n-butylamine N,Ndithio-bis-di-isobutylamineN,N-dithiobis-di-namylan1ine N,N-dithio-bis-di-isoamylamineN,N-dithio-bis-n-hexylamine N,N'-dithio-bis-di-n-heptylamineN,N-dithio-bis-di-n-octylamine N,N'dithio-bis-diabenzylamineN,N-dithio-bis-rnethyl cyclohexylamine N,N-dithio-bis-ethylcyclohexylamine N,N'-djthiobis-(thiomorpholine)N,N'-dithio-bis-(4-N-ethyl piperazine) N,N'-dithio-bis-piperidineN,N-dithiobis-pyrrolidine The N,N'-thio-bis-di-secondary amines and N,N'dithiobis-di-secondary amines constitute a preferred class.

The mercapto azoles which can be used include the mercaptothiazoles,mereaptoimidazoles and the mercaptooxazoles. Either aliphatic oraromatic azoles can be used. Representative examples are:

Z-mercaptothiazole 2-mercaptooxazole 2-mercaptoimidazole2-mercapto-4-methylthiazole 2-mercapto-4-methyloxazole2mercapto-4-methylimidazole 2-mercapto-4-ethy1thiazole2mercaptot-methyloxamle 2-mercapto-4-methylimidazole2-mercapto-4-n-propylthiazole 2mercapto-4-n-propyloxazole2rnercaipto-4-n-propylimidazole 2mercapto-4-n-butylthiazole2-mercapto-4-n-butyloxazole 2-mercapto-4-n-butylimidazole2-mercapto-4,5-dimethylthiazole 2-mercapto-4,5-dimethyloxazole2-mercapto-4,S-dimethyl-imidamle 2-mereapto-4,S-diethylthiazole2-mercapto-4,S-diethyloxazole 2-mercapto-4,5-diethylimidazole2-mercapto-4,5-di-n-propylthiaz0le Z-nrercaptoi,S-di-n-propyloxazole2-mercapto-4,S-di-n-propylimidazole 2-mercapto-4,5 di-n-hutylthiazole2-mercapto-4,5-di-n-butyloxazole 2-mercapto-4,5-di-n-hutylimidazole4-phenyl-Z-mercaptothiazole 4-phenyl2-mercaptooxazole4-phenyl-2-mercaptoimidazole 4-phenyl-5-methyl-2-mercaptoth.iazo1e4-phenyl-S-methyI-Z-mercaptooxazole4-phenyl-5-methyI-Z-mercaptoimidazole Z-mencaptobenzothiazole4-phenyl-2-mercaptohenzothiazole G-phenyl-Z-mercaptobenzothiazoleZ-mercapto-tetrahydrobenzothianole 2-mercapto-naphthothiazole Solventscan often be used to an advantage in carrying out the invention.Suitable solvents are the lower aliphatic alcohols such as methanol,ethanol, isopropanol, n-propanol, n-butanol, and other common organicsolvents such as chloroform, benzene, trichloroethylene, toluene andxylene.

Higher or lower temperatures than the reaction temperatures of theexamples can be employed. The reaction temperature is not critical, butit is desirable to use a temperature that will allow a reasonably rapidrate of reaction, so that the preparation can be carried outeconomically.

While certain representative embodiments and details are shown hereinfor the purpose of illustrating the invention, it will be apparent tothose skilled in the art that various modifications may be made thereinwithout dcparting from the spirit or scope of the invention.

We claim:

1. The method of preparing an amino azole disulfide which comprisesreacting (a) an amine disulfide of the general formula:

in which the nitrogen substituents, Rs, are selected from the classconsisting of aliphatic radicals, cycloaliphatic radicals, aralkylradicals and cycloaliphatic rings formed b the joining together of thepair of R's on a nitrogen atom with (b) a mercapto azole selected fromthe class consisting of mercaptothiazolcs, mercaptoimidazoles, andmercaptooxazoles, said amine sulfide being reacted in the ratio of onemole of said amine sulfide to from one to two moles of said mercaptoazole.

2. The method of preparing an aminothiazole disulfide which comprisesreacting (a) an amine disulfide of the general formula in which thenitrogen substituents, R's, are radicals from the class consisting ofaliphatic radicals, cycloaliphatic radicals, aralkyl radicals andcycloaliphatic rings formed by joining together of the pairs of R's on anitrogen atom with (b) a Z-mercaptothiazole, said amine sulfide beingreacted in the ratio of one mole of said amine sulfide to from one totwo moles of said mercaptothiazole.

3. The method of preparing an aminobenzothiazole disultide whichcomprises reacting (a) an amine disulfide of the general formula inwhich the Rs are selected from the class consisting of aliphaticradicals, cycloaliphatic radicals, aralkyl radicals, and cycloaliphaticrings formed by the joining together of the pair of R's on a nitrogenatom with (b) a Z-mercapto'benzothiazole, said amine sulfide beingreacted in the ratio of one mole of said amine sulfide to from one totwo moles of said mercaptobenozthiazole.

4. The method of preparing an aminobenzothiazolc disulfide whichcomprises reacting in a solvent (a) an amine disulfide of the generalformula Rl u in which the R's are selected from the group consisting ofaliphatic radicals, cycloaliphatic radicals and aralkyl radicals, the Rsare selected from the group consisting of hydrogen, aliphatic radicals,cycloaliphatic radicals and aralkyl radicals, and R and R attached to asingle nitrogen atom can be joined with said atom to constitute atheterocyclic radical, with (b) a mercapto azole selected from the classconsisting of mercaptothiazoles, mercaptoimidazoles, mercaptooxazolcsand the alkali metal salts of said mercapto azoles, said amine sulfidebeing reacted in the ratio of one mole of said amine sulfide to from oneto two moles of said mercapto azole.

7. The method of preparing 2-(4-morpholinyldithio)- benzimidazole whichcomprises reacting N,N'-dithio bismorpholine withZ-mercaptobenzimidazole.

8. The method of preparing N-cyclohexyl henzothiazole-Z-thiosulfenamidewhich comprises reacting cyclohexylamine disulfide withZ-mereaptobenzothiazole.

References Cited in the tile of this patent UNITED STATES PATENTS2,835,670 Hardman May 20, 1958 UNITED STATES PATENT OFFICE CERTIFICATEOF CORRECTION Patent No, 3,100,773 August 13, 1963 George D. Louth eta1.

error appears in the above numbered pet- It is hereby certified that tthe said Letters Patent should read as ent requiring correction and thecorrected below.

Column 1, line 26, for "the", first occurrence, read are line 53, strikeout "into"; column 6, line 49, for

's" read R 's Signed and sealed this 15th day of March 1966.

(SEAL) Attest: r L

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner ofPatents UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No3 100 773 August 13 l 963 George D. Louth et a1 It is hereby certifiedthat error appears in the above numbered patent requiring correction andthat the said Letters Patent should read as corrected below.

Column 1, line 26, for "the", first occurrence, read are line 53, strikeout "into"; column 6, line 49, for "R's" read R s Signed and sealed this15th day of March 1966 (SEAL) Attest: 1'

ERNEST W. SWIDER Attesting Officer EDWARD J. BRENNER Commissioner ofPatents

1. THE METHOD OF PREPARING AN AMINO AZOLE DISULFIDE WHICH COMPRISESREACTING (A) AN AMINE DISULFIDE OF THE GENERAL FORMULA:
 5. THE METHOD OFPREPARING 2-(4-MORPHOLINYLDITHIO) BENZOTHIAZOLE WHICH COMPRISES REACTINGN,N''-DITHIO-BISMORPHOLINE WITH 2-MERCAPTOBENZOTHIAZOLE.